Arkane raises a good point. Depending on how the questions in the survey were phrased, some of the respondents might have said that they were carrying a balance when they meant reporting a balance. Even people who are readers of these forums will often use the phrase "carry a balance" when they mean report.
Without getting access to the exact wording for the questions we can't know how reliable this journalist's piece is.
We do know that the journanist is confused about some things. For example the journalist claims that carrying a balance is the same thing as making the minimum payment, which it is not.
Another way the survey wording could lead to mistaken conclusions is failing to distinguish between engaging in a behavior once in the past and regularly engaging in it now. In my own case, for example, I carried a small balance for a few months about 12 years ago because I thought it would improve my credit. But then I learned better and have not done so since. Classifying me in the group that is misinformed because of doing something once 12 years ago is like calling somebody a smoker because he smoked one cigarette 20 years ago. If you look closely at the wording here, you'll see that there is a likely conflation of past vs. present behavior:
"The study also found that 27 percent of cardholders without a college degree have done this, versus 12 percent with a college education. And 30 percent of credit-card users making less than $50,000 a year have wrongly sought to improve their credit scores by carrying a balance, compared to 19 percent of those earning more than $50,000."
Have done this, is past tense, and could mean have done this once in their lives many years ago. As opposed to are doing this. Likewise have wrongly sought is past tense compared with are wrongly seeking.
